Distance measurement apparatus and related methods

Abstract

A distance measurement apparatus arranged to measure the distance to an object (106) comprising a first sonic transmitter (100) arranged at a first distance (h1) from that object and a second sonic transmitter (102) arranged at a second distance (h2) from that object (100), wherein the first and second distances are different, the first (100) and second (102) transmitters being controlled by processing circuitry (108) and the first and second transmitters being arranged such that sonic pulses emitted, in use, thereby are incident upon that object (106) and the apparatus further comprising at least one sonic receiver (100) arranged to receive a plurality of reflected sonic pulses and generate an output therefrom and the processing circuitry (108) being arranged to receive the output, determine the times since the first and second pulses were emitted and generate a distance to that object from the determined times.

1. A distance measurement apparatus arranged to measure the distance to an object, the apparatus comprising:
 a first sonic transmitter; 
 a second sonic transmitter; 
 wherein the first and second sonic transmitters are arranged to be at different distances from the object, the first and second transmitters being controlled by processing circuitry and the first and second transmitters being further arranged such that the first and second sonic pulses emitted respectively therefrom are incident upon the object; and 
 a single sonic receiver arranged to receive reflected sonic pulses and generate an output therefrom; 
 wherein the processing circuitry is arranged to receive the output, determine the times since the first and second pulses were emitted and generate a distance to the object from the determined times. 
 
     
     
       2. The distance measurement apparatus according to  claim 1 , wherein the first and second transmitters emit the first and second sonic pulses at substantially the same time. 
     
     
       3. The distance measurement apparatus according to  claim 1 , wherein the first and second sonic pulses are ultrasound pulses. 
     
     
       4. The distance measurement apparatus according to  claim 1 , wherein one of the sonic transmitters is also a receiver. 
     
     
       5. The distance measuring apparatus according to  claim 1 , wherein a sonic receiver is mounted at substantially the same distance from the object as one of the transmitters. 
     
     
       6. The distance measuring apparatus according to  claim 1 , wherein the first and second transmitters are arranged such that they emit the first and second sonic pulses which travel along lines substantially perpendicular to the object. 
     
     
       7. The distance measuring apparatus according to  claim 1 , in which the first and second transmitters are offset from one another, in a direction substantially transverse a perpendicular line between one of the first and second transmitters and the object. 
     
     
       8. The distance measuring apparatus according to  claim 7 , in which the offset is small such that a reflected sonic pulse received by the receiver has traveled substantially along a line perpendicularly to the receiver from the object. 
     
     
       9. The distance measuring apparatus according to  claim 1 , wherein the object to which a distance is to be measured comprises a surface of a liquid. 
     
     
       10. The distance measuring apparatus according to  claim 9 , in which the surface of a liquid is flowing through a weir or flume. 
     
     
       11. The distance measuring apparatus according to  claim 10 , wherein the processing circuitry is further arranged to utilize the distance measured to calculate the flow of liquid through a channel in which the weir or flume is positioned. 
     
     
       12. A method of measuring the distance to an object, the method comprising:
 timing a first time of flight of a first sonic pulse emitted from a transmitter at a first distance from the object; 
 timing a second time of flight of a second sonic pulse emitted from a transmitter at a second distance from the object, and 
 using the first and second times of flight to calculate the distance from a receiver to the object, the receiver used to receive the sonic pulses. 
 
     
     
       13. The method according to  claim 12 , wherein the sonic pulses are emitted from one or more transmitters at substantially the same time. 
     
     
       14. The method according to  claim 12 , wherein the sonic pulses comprise ultrasound. 
     
     
       15. The method according to  claim 12 , wherein one of the transmitters includes a receiver. 
     
     
       16. The method according to  claim 12 , wherein the method is utilized in measuring the level of a fluid in a tank or in determining the rate of flow of liquid in a channel. 
     
     
       17. A non-transitory machine readable medium comprising instructions that when read by a processing circuitry cause said processing circuitry to perform the method of  claim 12 .